The present disclosure relates to the field of fluid flow control and, more particularly, to a solenoid valve. Even more particularly, the present disclosure relates to improvements in solenoid-actuated proportional-control valves, and, in one particular aspect, to a unique and advantageous electrically operated fluid valve of low-cost and uncomplicated construction which accurately controls high-volume flows with the aid of a frictionless suspension and a pressure-counterbalancing bellows cooperating with its movable valve member.
Fluid valves exist in a wide variety of forms and sizes, serving a multitude of purposes, handling flowable materials whose characters range from light gaseous to heavy slurries and near-solids, and operable at various speeds under controls as diverse as simple binary (ON-OFF), proportional, direct-manual and remote-electrical. Those which are capable of responding quickly to govern even relatively large flows with precision, and with expenditure of little electrical power, are of special interest in certain industrial processing, such as the automatic regulation of gases in semiconductor and integrated-circuit manufacture. Mass flow controllers, for example, are widely used in the manufacturing to control the delivery of process gases, and the mass flow controllers include such valves.
A problem previously encountered with such valves was adverse effects of line pressures on valve members of the valves at or near closure of the members. Another problem was the large control forces which were needed to overcome friction and valve broad-area flow passages in accommodation of high rates and volumes of flow.
In response to these problems, U.S. Pat. No. 4,796,854 (the ""854 patent) provides a proportional-control solenoid-actuated fluid valve, capable of governing relatively large volumes and rates of flow swiftly and accurately with expenditure of relatively little electrical power. The disclosed valve includes a movable valve member positioned by an armature having a substantially frictionless spring suspension, the armature being under influence of a special force-counterbalancer in the form of a bellows proportioned and disposed to exert upon it, automatically, neutralizing forces which are substantially equal and opposite to unavoidable pressure-induced imbalances afflicting the valve member. The same pressures which tend to unbalance the valve member are impressed upon opposite sides of the bellows, one through an enabling bleed port, and resulting forces developed by the bellows over a defined area are exerted upon the armature mechanically in a counterbalancing sense.
Other examples of more refined valve assemblies can be found in the Type 1479 and Type 1640 mass flow controllers available from MKS Instruments, Inc. of Andover, MA.
The previously existing designs, accordingly, provide excellent proportional-control solenoid-type valves which can swiftly and accurately govern even relatively large volumes and high rates of fluid flow using relatively low levels of electrical power, since the valves are aided by the force counterbalancing achieved through the use of the bellows-type coupling. The previously existing valve assemblies also provide sensitive and precise valving by way of the frictionless suspension of broad-area valve members and the counterbalancing of undesirable pressure-generated forces through a correlated pressure-responsive coupling.
What is still desired, however, is a valve assembly providing all the benefits of these previous valve assemblies, yet which has a simpler design including fewer components.
The present disclosure, accordingly, provides a valve assembly including a body having an inlet port, an outlet port, and a valve seat having a passageway connecting the inlet and the outlet ports. A valve member is movable along an axis extending through the passageway of the valve seat to close and open the passageway, and an electrical solenoid assembly moves the valve member upon being energized to control fluid flow between the inlet and the outlet ports.
The valve assembly also includes a fluid-tight bellows positioned within the body to apply a force to the valve member in opposition to a force applied to the valve member by the fluid flow between the inlet and the outlet ports. A pressure balancing passageway connects the inlet port to the bellows.
The valve assembly further includes a housing received over the solenoid assembly and having a flange received against the valve body. A seal is positioned between the flange of the housing and the valve body, and a collar is secured in a continuous manner to the valve body over the housing flange, thereby securing the housing to the valve body and applying a sealing force to the seal in a substantially even manner.
The valve assembly according to the present disclosure provides all the benefits of prior existing valve assemblies, yet has a simpler design including fewer components that are easier to assembly together during manufacturing.
These and other features and benefits of the present disclosure will become more apparent upon reading the following detailed description in combination with the accompanying drawings.